Baler wire tying mechanism



Aug. 28, 1951 G. L. BURKETT 2,566,054

BALER'WIRE TYING MECHANISM Filed oct. 1o, 1945 4 sheets-sheet 1 '3121 a if j Z9 41 f1 G. L. BURKETT BALER WIRE TYING MECHANISM Aug. 28, 1951 2,566,054

Filed Oct', l0, 1945 4 Sheets-Sheet 2 Aug. 28, 1951 G. l.. BuRKl-:TT

BALER WIRE TYING MECHANISM 4 Sheets-Sheet 4 Filed Oct. l0, 1945 VrI mi' Patented Aug. 28, 1951 U N l TED STAT ES PATENT OFFICE BALER WIRE TYING MECHANISM Griffith L. Burkett, Martinsville, Ind.

Application October 10, 1945, Serial No. 621,485

VThe present invention relates to wire tying Vmechanism, and it is primarily concerned with the problem of producing a satisfactory tie in 'baling wire when'used to confine a bale of hay, straw, or similar material, before discharging such bale from the'baling mechanism. Suitable,

Vsecuring a bale of tightly compressed material are obvious, and it has long been the desire of balermen to be provided with means for suitably knotting wire.

Devices whereby the ends of a wire surrounding a bale of material may be twisted together have been known heretofore, but mere twisting does not satisfactorily secure the Wire ends together, and furthermore the twisted stubs of wire projecting 'from the bale have been 4found to be dangerous inasmuch as persons have frequently been injured by such projections during the handling of the nished bales.

The primary object of the invention, then, is to provide means for tying a suitable knot in baling wire, such means being of such character that the bale is bound in the baling machine, the binding wire is knotted, the wire is then cut, andthe bale is discharged from the machine, -a new strand of wire 'being suitably positioned automatically for binding a subsequent bale. Further objects of the invention will appear as `the description proceeds.

To the accomplishment ofthe above'and related objects, my invention may be embodied inthe form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that change may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.

Fig. 1 is a 'fragmentary plan viewof a baler with which my tying mechanism is associated;

Fig. 2 is a side elevation of the same `fragment of a baler illustrated 'in Fig. 1;

Fig. 3 is an enlarged detail of a portion'of the driving means for'my tying mechanism taken `on the line 3--3 of Fig. 4; n

Fig. 4 is a horizontal section taken substantially on the line 4-4 of Fig. 3;

Fig. 5 is an enlarged fragmentary view of the timing .mechanism for my wire tying means,

2 Y parts being broken away for clarity o1' illustration;

Figs. 6 and 7 lare lenlarged fragmentary plan views of a portionof the wire handling mechanism, showing the needle in the position vwhich it assumes immediately before a new bale vis started, and inthe position which it assumes just as a bale is completed, respectively;

Fig. 8 is an enlarged 'horizontal section showing certain details of my wire tying mechanism;

Fig. 9 is a fragmentary view thereof, showing the bill hook after `itl'ras vbeen rotated to form a loop, and just before it assumes theposit'ion in uwhich the end of the wire is to be `drawn through the loop;

Fig. 10 is a vertical section taken on the line Ill-I0 of Fig. 8 and vshowing the Vparts A'in slight- 1y 'further advanced position;

Fig. 11 is a 4fragmentary section lupon l*the same plane, showing the parts after they wire has "been drawn through the loop;

Fig. 12 is a vertical section taken substantially on the line lI2--l2 vof Fig. l8;r

Fig. 13 is a vertical section taken in "a plane perpendicular to the plane of Figs. l0 and 12;

Fig. 14 is a further enlarged section of the holding and cutting mechanism taken upon a plane parallel to the plane ofrFig. 12;

Fig. 15 is a vertical fragmentary section taken upon the plane indicated Aby the line `I5|5 'of Fig. 14; and

Fig. 16 is a plan of the parts shown in Fig. 14.

Referring more particularly tothe drawings, vI

jhave illustrated a part of a standard `form oi 'balen indicated generally by the reference numeral 20, land comprising a baling chamber 2l. I have shown a power input pulley 22 connected to drive Aa bull wheel v22' with which `is associated a pitman 23 connected to reciprocate a plunger 24 which moves past a feed opening 25 in the chamber 2| to compact the material 26 to be baled. Y

Mounted adjacent `the feed opening `upon one vertical wall of the baling chamber is my 'wire tying mechanism, indicated generally by the reference numeral 21., and adapted to be driven by a chain 28 which runs .over suitable sprockets on the shaft of the bull wheel 22 and on the main shaft of the wire tying mechanism, respectively. Suitably supported to projectinto the baling chamber is a star wheel 29, so arranged `that, `as the `material 26 moves past the station of said star wheel, said wheel will be rotated `at a rate determined by the rate of movement yof such `material to measure the amount of I material passing such station. A pair of arms 38 are mounted, above and below the .baling chamber, to swing upon a journal 3| and on aligned stub shaft 3|', said arms carrying one or more needles 32. In the illustrated embodiment of the invention, I have shown an arrangement in which two of such needles are carried by the arms 38, and in which two of my tie mechanisms are provided, itbeing understood that there will be a needle and a tie mechanism for each strand of wire to be bound around each bale. Since the two needles are identical, and the two tie mechanisms are identical, and since the needles cooperate identically with their respective tie mechanisms, only one such assembly is illustrated in detail and will be described herein.

Each needle is arranged in registry with registering openings in the side walls of the baling chamber, indicated by the reference numerals 33 and 34 in Figs. 1, 6 and '1. A wire 35 leads from a source of supply, such as a spool supported on a suitable journal on the machine (not shown), past a guide pin 36 and through the eye 31 of the needle 32. The wire is threaded through said needle eye, which may be guarded by one or l' more rollers 38, and thence past a stop pin 39,

across the baling chamber 2|, past a stop pin 40, and to a holding means, indicated generally by the reference numeral 4|, and forming a part -of the tying mechanism. The details of the holding means 4| will be particularly described hereinafter.

As is clearly to be seen in Fig. 3, the chain 28 drives a sprocket 42 which carries a beveled gear 43 meshing with a beveled gear 44 loosely mounted upon a vertical shaft 45. Operatively associated with said gear 44 is a single revolution clutch, indicated generally by the reference numeral 45. This clutch includes a part fixed on the shaft 45 and a part engageable with the gear 44, and may be of any standard commercial type, such as the well known Hilliard single revolution clutch. One element 41 of said clutch projects into a position to be blocked by a finger 48, when said finger is in one of its selective positions, Said finger is mounted, intermediate its ends, upon a rock shaft 49, and its opposite end is pivotally associated, as at 58, with a rod which is slidably mounted upon one side of the baling chamber. A spring 52 normally holds the nger 48 in the solid line position illustrated in Fig. 4; and a stop element 53 limits the degree of movement of said finger in a clockwise direction under the influence of said spring. A stud 54 projects downwardly from that element of the clutch 46 which is fixed to the shaft 45, and vconstitutes a swivel mounting for one end of a. pitman 55 whose opposite end is pivotally connected to an arm 6| fixed on the shaft 3|' to which the lower arm 38 is fixed. The arrangement is such that, when the clutch 48 acts to clutch the gear 44 to the shaft 45, that portion of the clutch which carries the stud 54 will make one revolution, whereby the arms will vbe swung, Vin a clockwise direction, as viewed in Fig. 1, to the position of Fig. '1, and will then be returned to the position of Fig. 1.

A spring 58 normally holds the bar 5l in its position illustrated in Figs. 4 and 5. In that position, a vertical surface 51 near the end of the bar 5| is located in the path of a finger 58 upon a cam 59 carried on the shaft 68 upon which is mounted the star wheel 28. As said wheel is rotated by movement of material 28 through the baling chamber, the finger 58 will be carried into engagement with the surface 51, and will move the bar 5| to shift said bar and the finger 48 into the dotted line position of Fig. 4, thereby releasing the element 41, permitting engagement of the Hilliard clutch, and permitting a single rotation of the shaft 45. Before that rotation is completed, the finger 58 will have dropped off the surface 51, and the spring 56 will have returnedthe parts to the solid line position of Fig. 4, so that rotation of the shaft 45 will be arrested, by engagement of the element 41 with the finger 48, upon the completion of that single revolution. "f

Carried upon the shaft 45 (see Figs. 2 and 8) is a gear wheel 52 formed to provide two gear segments 63 and 64 upon separate radii. Mounted adjacent said gear 62 is a bracket 55 to which is secured a housing 86. Journalled in said bracket and said housing is a hollow shaft 61 which carries, at one end, a gear 68 designed and positioned to fbe engaged and driven by the gear segment 53. Associated with said gear 68 is a wheel 89 having a flat section designed to engage and cooperate with a flat segment 1| upon the gear Wheel 62. The parts are so proportioned that, as the gear 82 begins to rotate, from its position illustrated in Fig. 8, in a counter-clockwise direction, the segment 63 promptly comes into engagement with the gear 68 to produce one complete rotation of said gear and the shaft 8l', in a clockwise direction as viewed from the left of Fig. 8. Just before the segment 53 moves out of operative engagement with the gear 68. the segment 64 moves into engagement with the gear 81 (later to be described) to produce one complete rotation of said gear 81. The remainder of the rotation of the gear 82 will be accompanied by no further movement of either gear 68 or 81.

Intermediate its ends, the shaft 61 is provided with diametrically aligned longitudinally extending slots 12 through which extends a pin 13, carried by a collar 14 loosely mounted upon the exterior surface of the shaft 61. Said collar is externally grooved for the reception of a pair of pins 16 carried by a lever arm 15 fixed to a rock shaft 11 suitably journalled in the bracket 65.

Reciprocably mounted within the hollow shaft 81 is a rod 18, said rod being provided with a transverse bore in which is mounted the pin 13. It will thus be seen that the rod 18 will rotate with the shaft 61, but that said rod may be reciprocated, within said shaft, by rocking movement of the rock shaft 11. y

At its end opposite the end upon which is mounted the gear 88, the shaft 81 carries a bill hook 19 whose general conguration is standard. However, said hook is formed with an opening 8|) adjacent the root of its nose 83, and a finger 8|, pivotally mounted at 82 upon the extremity of the rod 18, projects through said opening 8|! and into cooperation with the curved inner surface 84 of said nose 83. In accordance with standard practice, the nose 83 of the bill hook is turned out of the axis of the shaft 61, and its outer surface 85 is curved in the manner shown.

It will be clear that, when the parts are in the positions illustrated in solid lines in Fig. 10, the finger 8i will be separated from the-inner surface 84 of the bill hook nose 83; but that, as the rock shaft 11 is turned in a counter-clockwise direction, the rear surface of the finger 8| will engage the edge of the opening 88 and the finger will thereupon be swung toward the surface 84 of the nose 83, and will be drawn downwardly along that mountedupon the shaft 86.

tremity is mounted a roller 9| for cooperation with the cam surface 92 of a rotor 93 loosely A spring 94 cooperates with said arm 99 to hold the rock shaft and its associated parts resiliently in the solid line position of Figs. and 12. Fixed to the shaft 8B is a plate 95 rprovided with means ||9 (see Fig. 13) for adjustably frictionally engaging the rotor 93, whereby a drive connection is established between the shaft 86 and the rotor 93. The rotor 33 is further provided with a finger 96 adapted to engage the roller-9| kto urge the parts positively into the solid line positions of Figs. 10 :and l2.

It will be seen that, as the rotation of the shaft 86 nears its end, the roller 9| will be shifted to the left, by the cam surface 92, to retract the rod 18, and that, 'as said shaft 86 completes rotation, said roller will be returned to the position of Fig. 8.

The shaft 86 likewise carries a worm 91 arranged to mesh with a worm wheel 98 mounted upon a sha-ft 99 suitably journalled in the housing 66 and carrying a'pair of plates |99 formed with knife-edged notches |97! at 4suitably periphf ported, by said linger, upon a spring |99 received upon the post |92 and resting at its lower end upon a nut threaded on said post. The plate |94 extends into cooperative relation with the drum |08 connecting the plates l 99, and is formed with a surface |01 conforming to the contour of said drum, said surface |91 being resiliently urged toward said drum |08 by the spring |09. Wires received in the notches |9| of the plates |99 are drawn along the surface |91 and crimped about said surface as shown in Fig. 14.

The post |92 integrally supports a plate ||9 in which is journalled a button eccentrically carrying a threaded post l2. At a spaced point, the plate H9 is provided with a perforation ||3 which is preferably threaded. A knife |I4 is perforated for engagement upon the element I2, and is adapted to be held in place thereon by a nut |15. Said knife is formed with an elongated opening through which passes a bolt IIB to engage in the perforation I3 of the plate H0. 'It will be seen that this mounting makes possible some adjustment of the position of the hooked blade ||1 of the knife I, with respect to the wheels |00.

The operation of the described `machine Ais as follows:

The wire having been threaded into the machine and engaged in one of the notches |91 of the wheels |09, and said wheels having -been turned to carry the engaged portions'of the 6 lwire intera position in vwhich Iit :crimped about the surface :|101 and 'between lthe wheels |99, it

will be seenA that a strand 35a of 'the .wire vexvtends transversely across the baling chamber. As vmaterial is yfed -to the Vbali-ng chamber and the plunger v21| is reciprocated, that material will en- .:g'agethe wire strand 35a .to move the same toward the left through the baling chamber, and `to producev a .bigh't of wire, one strand of :which extends from the :post 49 toward the discharge end of the baling ychamber along r.the adjacent aside of the baling chamber, another of which extends across `the front end of the 'bal-e being formedto v the opposite side of the fbaling chamber, and an- 'l other lof which lextends .along :said opposite side of `the 'baling ychamber tothe post `39, and thence Aout to the eye 31 :of the ,needle 32. The portion of the :Wire extending across `the `baling chamber willbe. designated as :strand 35a, that portion extending from the .post 49 kto -the strand V35a. will be designated 9519, that portion extending from ythea'strandxlct tothe post 99 Awill be-designatedstrand 315e, that :portion extending lbetween the fpcst 49 ,andthe 'holder 4| will `be designated strand 35d.

When a, suflicient amountof material has been `moved past the :star `wheel 2.9, the `clutch 46 will be tripped. Thereupon, the needle 32 will immediately be swung to the position of Fig. "1, Ythus carrying a strand of Wire, indicated by the referencenumeral 35e, across the baling .chamber behind kthe Vnewly formed bale, pastthe lrear surface of the bill hook and 'the finger 8|, and into contact Vwith :the peripheral surface of the wheels |80. That strand will usually `Vbe laid into the particular vnotch |0'| already Aoccupied by the strand 35d.; Ibut ifnit is not, the firstv movement of the'w-heels |90` will shift .the .strand .35e :into the desired notch. Now, lthe Ysegment 63 ofthe gea-r wheel 62 moves into coactive engagement with -t-he ywheel ,88, and the 'bill hook .begins to rotate inthe direction indicated by-the arrow in Fig. 8. Its'nose'promptly engages that portion `of 4the Kstrands 35d and 35e vlying between the bill hook and the baling lchamber, in the manner illustrated in Fig. 8. As the shaft 61 continues to rotate, the wire is wrapped about the finger 8| and the bill hook nose 83, so that a loop 35g is formed, as the shaft 61 completes 270 degrees of rotation and reaches the position shown'in Fig. 9. Meantime, the gear 81 has been engaged by the gear segment 64 to begin the rotation of the shaft 86, and, at this point, both wires are tightly gripped between the near wheel |00 and the plate |04, and the finger 99 is engaging the roller 9| to prevent the movement `of the rock shaft 11 out of the solid line positions of Figs. 19 and l2.

As the shaft 61 completes 'its rotation, the portion 35h of the two wire strands is brought'be- `tween the finger 8| and the inner surface 84 of the bill hook nose 83, in the manner clearly appreciable from a consideration of Fig. 9. At this instant, the roller 9| begins to ride up on the cam surface 92, whereby the finger 8| is rocked substantially into contact with the bill hook surface 8'4, thus engaging over the portion 35h. As the mechanism thus begins to retract the rod 18, the wheels |00 bring the wire portions engaged in the appropriate notch |9| into contact with the knife edge |1; and as'retraction of the rod 18 continues, to draw the end of the finger 8| downwardly along the surface 84, the wires are cut, and the wire ends are drawn through the loop 35g, in the manner illustrated in Fig. 11.

At vsubstantially this same time, the arms are returned from the position of Fig. '7 to the position of Fig. 6. Obviously the portion of the wire on that side of the knife H4 remote from the baling chamber 2| will be retained by the other wheel of the holder 4|; so that, as the needle swings back to the position of Fig. 6, the end of the wire is held in the holder, and the strand 351 of the wire is drawn across the baling chamber to occupy the position of the strand 35a in Fig. 6. Reference to Fig. 10 will show the relative position of said wire strand on the holder 4|.

Thus, the machine is prepared to begin the formation of a new bale, which will be completed and tied in the same manner.

A piece of wire extending from that notch |0| by which the cut was made, between the near wheel |00 and the plate |04 up over the edge |01 of said plate, and thence between said plate and the far wheel to the corresponding notch of said far wheel, cut from the strand d, will remain on the holder 4| as that section of the holder moves past the knife I I4. Such wire sections are to be perceived in Figs. 12, 14 and 16. Positioned between the wheels |00 and above the drum |08 is a stripper plate l I8 so proportioned and designed that it will be straddled by such wire section as such portion of the holder comes into registry therewith, whereby such wire section will be forcibly stripped off the wheels |00 and dropped away from the machine.

While the mechanism disclosed herein is, in many particulars, closely similar to previously known tying mechanisms used for knotting twine, it has been found in practice that such previously known mechanisms are almost completely inoperative when wire is threaded into them, whereas my provision of means for positively pulling the portion 35h of the wire down through the loop 35g renders the mechanism effective to produce a proper knot in baling wire with invariable eieca.

tiveness. So far as I am advised, I am the'flrst to have conceived means for automatically and positively pulling the end of the wire through the loop before the loop is permitted to slide over the nose of the bill hook.

I claim as my invention:

1. Wire tying mechanism comprising a bill hook adapted to be rotated about an axis and having a nose turned out of said axis, a reciprocator mounted to rotate on said axis with said bill hook, means for shifting said reciprocator longitudinally of said axis relative to said bill hook, power-actuated means for rotating said bill hook and reciprocator, a linger pivotally mounted on said reciprocator with its free end adjacent the inner surface of said nose, and means cooperating with said finger, upon shifting of said reciprocator in one direction, to force said finger end to engage and scrape along said inner surface of said nose from a point near the extremity of said nose toward the root of said nose.

2. In a wire tying mechanism, a bill hook comprising a hollow shaft and a nose turned out of the axis of said shaft, said shaft being provided with an opening adjacent the root of the inner surface of said nose, a rod reciprocably mounted in said hollow shaft, a iinger pivotally carried on said rod and projecting through said opening into cooperative relation with said inner surface of said nose, means for rotating said shaft, and means synchronized with said rotating means for retracting said rod as said shaft approaches the end of a rotation, whereby said finger engages an edge of said opening, is swung about its'pivotal mounting toward said inner surface of said nose, and is drawn along said surface toward the root of said surface.

3. A wire tying mechanism, for use with a bale tier of the type including a baling chamber, a wire holder at one side of said chamber, a needle whose point normally lies at the other side of said chamber, a source of wire supply, such wire extending from said source over a support on said needle point, across the interior of said chamber, to said wire holder, means to force material to be baled to flow longitudinally through said chamber carrying with it the portion of said wire traversing said chamber to form a bight of wire within said chamber, means actuated by movement of material through said chamber by said forcing means to cause said needle to traverse said chamber tov lay a strand of wire across the trailing end of a formed bale and to engage said strand in said holding means, means for moving said holding means after such strand has been laid, and means to retract said needle after initiation of movement of said holding means whereby a different strand of wire is laid in a newly-presented portion of said holding means, said wire tying mechanism comprising a bill hook including a hollow shaft and a nose turned out of the axis of said shaft, said hook being located between said holding means and the adjacent side of said chamber, said shaft being provided with an opening adjacent the root ci the inner surface of said nose, a rod reciprocably mounted in said hollow shaft, a finger pivotally carried on said rod and` projecting through said opening into cooperative relation with said inner surface of said nose, the portion of said wire extending from the adjacent side of said chamber to said holder lying behind said finger, and such needle acting to lay its strand alongside said wire portion and also behind said finger, means for rotating said shaft to cause said nose to engage said wire portion and said strand at a point between the axis of said shaft and said chamber and to produce a loop of said wire portion and said strand enclosing said nose and said ringer, and further to engage, between said nose and said ringer and traversing said loop, a part of said wire portion and said strand located between said loop and said holder, and means acting after such last-named engagement has been produced to retract said rod, whereby said nger engages an edge of said opening, is thrown into cooperative engagement with said last-named part of said wire portion and said strand, and is moved toward the root of the inner surface of said nose to draw said Wire part positively through said loop.

4. Wire tying mechanism comprising a bill hook adapted to be rotated about an axis and having a nose turned out of said axis and including an inner curved surface, a finger associated with the inner curved surface of said nose, a reciprocator mounted to rotate on said axis with said bill hook and for reciprocation longitudinally of said axis relative to said bill hook, said reciprocator being operatively connected to said nger for movement relative thereto and acting, upon mov-ement in one direction relative to said bill hook, to force the end of said ringer to scrape along said inner curved surface of said nose from a point near the extremity of said nose toward the root of said nose, and power means for rotating said bill hook and reciprocator and for reciprocating said reciprocator.

5. For use with a baling machine including a baling chamber, means for grasping portions of the ends of a wire extending around a bale in such a baling chamber in the form oi a loop, a bill hook formed of two relatively movable parts, means for rotating said bill hook while in eri-- gagement with the ends of the wire inwardly of the grasped portions thereof to form a bight therein, means for spreading the parts to receive portions of the ends of the Wire, means for closing the parts to retain the last-mentioned wire portions, and means for moving said parts relatively longitudinally to draw said last-mentioned portions actively through said bight while said parts remain in closed position to hold said bight upon said bill hook.

6. For use with a baling machine including a baling chamber, means for grasping portions of the ends of a wire extending around a bale in such a baling chamber in the form of a loop, a bill hook comprising an element rotatable about an axis and having a nose turned out of said axis, means for rotating said element about said axis to cause said nose to engage said wire to form a double bight therein inwardly of the grasped portions thereof, a finger operatively associated with said nose, means movable relative to said element and operable, during rotation of said element and after formation of such bight, to spread said finger from said nose to receive portions of the ends of said wire therebetween in traversing relation to said bight, said means being operable thereafter to swing said finger into engagement with said nose adjacent the outer end thereof in retaining relation ,to said last-mentioned wire portions, and to move said finger from the outer end of said nose toward the root thereof to draw said last-mentioned wire portions positively through said bight, and means engaging said finger, during such last-mentioned movement thereof, and holding said finger positively in engagement with said nose.

7. In a wire-tying mechanism, a bill hook comprising an element rotatable about an axis and having a nose turned out of said axis, means for rotating said element about said axis, a finger operatively associated with said nose, a reciprocator mounted to rotate on said axis with said bill hook and reciprocable longitudinally of said axis relative to said bill hook, said reciprocator being operatively connected to said finger for movement relative thereto, means operable during rotation of said element to shift said reciprocator in one direc-tion relative to said bill hook, means cooperable with said finger, upon such shifting of said reciprocator, to spread said finger from said nose, and means operable thereafter to shift said reciprocator in th-e opposite direction to swing said finger into engagement with said nose ad= jacent the outer end of said nose and to move the same, while in such engagement, longitudi= nally of said nose toward the root thereof.

8. For use with a baling machine including a baling chamber, means for grasping portions of the ends of a baling wire extending around a bale in such a baling chamber in the form of a loop, and means for forming a tie in the ends of the wire inwardly of the grasped portions thereof including mechanically-driven rotating means engageable with said wire ends for forming a bight in the ends of the wire, means for shifting said grasping means during rotation of said rotating means to lay portions of the wire ends across said bight, and means reciprocable relative to said rotating means for engaging and positively drawing the last-named Wire portions through the bight.

9. Wire tying mechanism comprising a bill hook including a hollow shaft and a nose turned out of the axis of said shaft, said shaft being provided with an opening adjacent the root of the inner surface of said nose, a rod reciprocably mounted in said hollow shaft, a finger pivotally mounted on said rod and projecting through said opening into cooperative relation with said inner surface of said nose, means for rotating said shaft, and actuating means for said rod acting, during rotation of said shaft, to project said rod, thereby swinging the free end of said finger away from said nose, and thereafter to retract said rod, thereby engaging the rear surface of said finger with an edge of said opening and throwing said finger end into cooperative engagement with said surface of said nose adjacent the outer end thereof and dragging said finger, while in such engagement, toward the root of said surface.

GRIFFITH L. BURKETT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Numbel 

